It is known that plasma torches have a complex structure, consisting of an electrical system, a pneumatic system, and a hydraulic system, so that their maintenance requires the services of very well qualified technicians highly competent in electricity, in pneumatics and in hydraulics. This results in such maintenance being particularly expensive.
Moreover, maintenance aid devices are already known for apparatus including an expert system capable, from a knowledge base describing elements linked together constituting an apparatus and the corresponding topology of the links, and of rules governing their behavior, of deducing the identity of a defective element of said apparatus from observation of the state of a certain number of these elements. In effect, these defective elements give rise to the existence of an abnormal state for a certain number of observable elements which are, a priori, all suspect, which defines a subassembly from among the elements as a whole. The size of this subassembly is progressively reduced by successive deductions by the expert system, these deductions being arrived at by means of a dialog with an operator who has to supply information in response to questions posed by this expert system and allowing him to resolve the ambiguities as to the possibility of breakdown in the suspect elements. He thus arrives at a routeing, including, at each step, called node, a subassembly of suspect elements, said information making it possible to pass, via one branch of this routing, to a downstream node relating to a part of the subassembly, the elements of the eliminated part of this subassembly no longer being suspect. Hence, in principle, a subassembly of reduced size, such as an electronic module or a defective component, is identified.
This routeing, as set out above, is however fairly theoretical since, in practice the choice of said branches cannot be made in an entirely deterministic way, since the number of possible observations of the elements is limited. That being so, said information supplied by the operator often makes it possible only to obtain a probability of the presence of a breakdown in a subassembly, switching the routeing to one branch of a node in preference to another. That being so, the expert system, or the operator, may be led to an impasse, making it necessary to set off again to the, or an, upstream node and explore other branches.
Moreover, for supplying information to the expert system or repairing the apparatus, the human operator has to consult documentation, such as diagrams, documentation from the manufacturer of the various elements, or repair sheets, which are often very voluminous and non-uniform, which does not give this operator an overall view. The quality of said information supplied and that of the repair then run the risk of depending on the qualification of the operator, while the time spent in research will be considerable if the apparatus is complex.
From the above it therefore results that, as a consequence of the complexity of a plasma torch, it would be difficult, if not impossible, to use a known maintenance aid device for maintenance of such a plasma torch.